Subsurface heating system and unit therefor



M. FREEMAN Feb. 8, 1966 SUBSURFACE HEATING SYSTEM AND UNIT THEREFOR Filed July 25, 1963 FIG.|

o o o 0 o o o o 0 o o o o o o o t o 0 Hw 0.. o o o o o o o o Q/L ..l M u INVENTOR. MA UR/Cf FAEE MN ATT R EY United States Patent ,Filed July 25,1963, Sel'. No. 297,589

7 Claims. (Cl. 219213) The present invention relates to a subsurface heating installation, particularly to installation for the heating of outdoor surfaces subject. to heavy traffic, as street pavements, outdoor walks, or thelike, to keep them free of snow and ice, and especially to electrically energized heating units or panels for use in such installation.

Itis an object of the present invention to provide heating units for subsurface heating installation of the Character described which are relatively compact and of light weight and yet rigid and sturdy to resist damage from weight pressure such as it might be subjected to from heavy traffic.-

It is also an object of the present invention to provide heating units for such subsurface heating installation which may be prefabricated at place of manufacture and readily and easily and conveniently transported to a place of use and there installed, withoutthe need for undergoing any additional processing or structural modification at such place.

It is another object of the present invention to provide heating units of the character described, that may be completely integratedwith the pavement in which they are installed, It is still another object of the present invention to provide heating units of theIcharacter describedwhich may be readily, simply andeasily connected to an electrical circuit servicing the installation with a minimum of time and a minimum of labor. It is a further object of the present invention to provide heating units of the character described in which electric heating elements orlresistances are protected to a maximum; against damage by friction or pressure.

It is yet a further object of the present invention to providesu-bsurface heating installations or systems that are highly efficient in the utilization of the heat generated in them for its, object of heating the surface above it, with a minimum of heat loss.

It is still a further object of the present invention to provide a subsurface heating system composed of individual heating units or panels of the character described which mayeachb'e individually connected in an elec tric circuit, so that the portion of the system as a whole will be affected to a minimum when any one unit is out of order; the remaining units in the installation not being affected thereby; and in which any defective unit may be readily repaired or replaced with the disturbance of but a minimum of pavement area; thereby assuring substantially continuous operation of the system with substantially minimum interference with traffic.

The foregoing and other objects and advantagesof the subsurface heating installations and of the heating units used thereforof the present invention will become more readily apparent to those skilled in the art from the embodiment thereof shown in the accompanying drawings and from the description following. It is to be understood, however, that such embodiment is shown by way of illustration only, to make the principles and practice of the invention more readily comprehensible, and without any intent of limiting the invention to the specific details therein shown.

In the drawings:

FIG. 1 is a more or less diagrammatic, top plan view of a subsurface heating installation embodying the present invention; with one of the heating units or panels 3,234,355 Patented Feb. 8, 1966 shown in full and broken across to indicate indeterminate length, and partly broken away to show structural detail; such unit shown as connected to an electric circuit by a splicing box joining it with the other units; the latter units shown in fragment; and

FIG. 2 is a section taken along the line 2-2 of FIG. 1 showing the installation embedded in the pavement.

Referring now in greater detail to the embodiment of the present invention illustrated in the drawings, the same show the subsurface heating installation composed of a group of units, namely four units or panels; each such panel or unit preferably consists of a housing, preferably of sheet metal and prefabricated of rectangular shape, comprising a receptacle portion, generally designated as 10, formed with a bottom wall 12, and an upstanding flange or side wall 14. The receptacle or box 10 may be relatively shallow in depth, not greatly exceeding the thickness of the suitably insulated electric heating element or wire 16 disposed therein, as hereinafter explained. The receptacle 19 is formed with a plurality ofpreferably circular openings 18, in its bottom wall 12, arranged preferably in evenly spaced rows. At least some of the openings, including the end ones, in each row, may be formed with an inwardly extending flared flange 20, that overhangs the marginal edge portion of such opening for a purpose which will hereafter be made clear.

Each of the units also comprise a cover portion for the box 10, generally designated as 22, .and comprising a top wall 24, and a depending flange 26. The top wall 24 may likewise be provided with rows of evenly spaced openings 28, which may preferably be the same size of the opening 18 and may be arranged to'register with the opening 18. g

In assembling the unit, the heating element 16, may be zig-zagged across the bottom 12 of the box 10, starting from adjacent a common opening 18, such as 18a, alongside of an edge of the box 10, preferably a corner thereof, such as the opening 18a, by being laid and tensed against the flanges 20 of the flanged openings 18, in, any desired, suitable arrangement such as the arrangement indicated in FIG. 1 of the drawings. The heating element 16 may be anchored in such position in any desired, suitable manner. It will be apparent that, thus arranged, the heating element 16 will be, at least partly in the curvature of the flanges 20 of the flanged holes 18, adjacent which it is tensed and held thereagainst against being shifted and otherwise disturbed. It will be understood that when only selected holes 18 are flanged, at least such holes should be selected as will provide pivot points for the zigzag pattern selected for the .heating element 16. Both ends of the heating element 16 may then be connected to splic ing wire '30, which may be passed to the exterior of the housing through the cover opening 28a, in register with the opening 180.

It will also be apparent that the cover 22 when positioned in the box 10 will not only 'be supported by the edges of the box flange 14, but also along its entire top wall area by the edges of its opening 26 resting on the flanges 20, so that such cover 22 does not contact the heating element 16 in any manner that might damage it or its insulation.

The heating unit thus described may be readily and economically produced and assembled at a central point of production and is compact and of light weight to be readily and easily transported to the point of use. At the point of use, the unit may be connected into the installation with one to four additional units by means of a splicing box 32. Such splicing box may consist of a receptacle or box generally designated as 32, including a bottom wall 34 and an upstanding flange 36, and of a cover, generally designated as 38, including a top wall 40 and depending flange 42. The bottom wall 34 of the receptacle may be formed with openings 44, which may be arranged to register with the opening 18a, in each of the heating units in the installation with which it is to be used.

A threaded eyelet 46 is then passed through the lead opening 28a in the unit and into the corresponding opening 44 in the splicing box and the splicing wires at the end of the heating element of the unit and passed into the splicing box through such eyelet. The eyelet may receive a nut 48 within the box 32, which may secure the bottom of the splicing box to cover 22 of the unit and, above the nut 48, a threaded bushing sleeve 50. A cable or main lead wire 52, connected in an electric circuit may be passed through the receptacle 32 of the splicing box and the splicing wires, from each unit connected thereto, to thereby electrically connect the unit in the electric circuit. The cover 38 of the splicing box may then be put into place.

Preferably the top wall 40, of the splicing box cover 38, may overhang the depending flange 54 along its edge forming a hollow into which paving material may be poured, such flange and paving material being of a height to bring the level of the splicing box even with the level of the paving over the unit.

After the units are in place on the pavement base 58, and connected in the system through the splicing box, as set forth above, the surface paving material 60 may be poured the'reover to a height to bring it to a level with the top surface of the cover 38 of the splicing box. It will be readily apparent that when the paving 60, which may be of concrete, is poured over the unit, it will enter into the unit through the openings 26 of the cover 22 and fill up the box 10, and through the opening 18 in the box fuse or connect with the supporting or base paving layer 48, to thereby safely and securely anchor the unit.

This completes the description of the subsurface heating units of the present invention and of the heating system in which they may be installed. It will be apparent that such heating units are of relatively simple construction, compact and light weight, and easily and economically assembled and electrically inter-connected into a continuous self-grounding electric system and installed in a pavement. It will also be apparent that the heating unit of the present invention is strong, sturdy and trouble-proof to a maximum and that systems into which they are connected are likewise highly efficient and capable for prolonged use and operation and may be adjusted and repaired without undue stoppage of and interference with the working of the system and with a minimum of time and labor.

It will further be apparent that numerous modifications and variations may be made in the subsurface heating unit of the present invention and in the systems in which they may be connected and installed, by any one skilled in the art, in accordance with the principles of the invention hereinabove set forth and without the exercise of any inventive ingenuity. I desire, therefore, the protection of the patent law for any and all such modifications and variation that may be made within the spirit of the invention and the scope of the claims hereto appended,

What I claim is:

1. A heating unit for subsurface heating installation, comprising a relatively shallow tray including a bottom and an upright flange, said bottom having a plurality of spaced openings formed therein arranged in spaced rows at least selected of said openings in each of said rows including the end openings of each of said rows, each formed with an inwardly extending outwardly flared flange overhanging the marginal edge portion thereof, and an electrical heating element arranged in zig-zag manner on said bottom between said rows of openings disposed against said flanges, a cover for said tray including a top wall and a depending flange adapted to fit on the exterior of said flange of said bottom, said top of said cover having a plurality of openings formed therein, said heating element having each of its ends terminate adjacent one of said cover top openings, each said end having a splicing wire secured thereto extending through said opening.

2. The heating unit of claim 1, wherein said openings in said cover are arranged to register with the openings of said tray bottom.

3. The heating unit of claim 1, wherein said one opening is disposed adjacent an edge of said cover.

4. The heating unit of claim 1, in combination with a splicing box, said splicing box comprising a bottom section including a bottom wall and an upright flange, said bottom wall having at least one opening formed therein, a threaded eyelet engaging the underside of said unit cover and passing through said one opening thereof through said opening in said splicing box bottom, means engaging said eyelet within said splicing box bottom securing said splicing box bottom to said unit cover, said splicing wires extending into said splicing box through said eyelet, said splicing box bottom adapted to have a cable connected in an electrical circuit passed therethrough and said splicing wires adapted to be connectedto said cable.

5. The combination of claim 4, wherein said splicing box includes a cover comprising a top wall and a depending flange fitted over the flange of said bottom.

6. The combination of claim 5, wherein said cover top is formed with an upright flange along its edges, forming a tray, and paving material is disposed within said tray.

7. The combination of claim 5, wherein said splicing box cover top wall extends beyond the said depending flange thereof and is formed with an upright flange at its edges forming a tray, said tray filled with paving material.

References Cited by the Examiner UNITED STATES PATENTS 2,042,742 6/1936 Taylor 219-21 2,511,378 6/1950 Roberson 219-345 2,932,711 4/1960 Adams 219-345 3,146,298 8/1964 Ceglice 174-49 FOREIGN PATENTS 286,807 3/ 1928 Great Britain.

RIC RD M. WOOD, Primary Examiner. 

1. A HEATING UNIT FOR SUBSURFACE HEATING INSTALLATION, COMPRISING A RELATIVELY SHALLOW TRAY INCLUDING A BOTTOM AND AN UPRIGHT FLANGE, SAID BOTTOM HAVING A PLURALITY OF SPACED OPENINGS FORMED THEREIN ARRANGED IN SPACED ROWS AT LEAST SELECTED OF SAID OPENINGS IN EACH OF SAID ROWS INCLUDING THE END OPENINGS OF EACH OF SAID ROWS, EACH FORMED WITH AN INWARDLY EXTENDING OUTWARDLY FLARED FLANGE OVERHANGING THE MARGINAL EDGE PORTION THEREOF, AND AN ELECTRICAL HEATING ELEMENT ARRANGED IN ZIG-ZAG MANNER ON SAID BOTTOM BETWEEN SAID ROWS OF OPENINGS DISPOSED AGAINST SAID FLANGES, A COVER FOR SAID TRAY INCLUDING A TOP WALL AND A DEPENDING FLANGES ADAPTED TO FIT ON THE EXTERIOR OF SAID FLANGE OF SAID BOTTOM, SAID TOP OF SAID COVER HAVING A PLURALITY OF OPENINGS FORMED THEREIN, AND HEATING ELEMENT HAVING EACH OF ITS ENDS TERMINATED ADJACENT ONE OF SAID COVER TOP OPENINGS, EACH SAID END HAVING A SPLICING WIRE SECURED THERETO EXTENDING THROUGH SAID OPENING. 